"The number one cause of proximity switch failure is physical contact with the target," notes Roger Varma, product manager for efector (Exton, PA). "With extended range and a setup LED, quadronorm plus(TM) switches will significantly reduce those failures."
Here's how these inductive proximity switch improvements are realized. Optimized geometry and core material give twice the range of conventional switches. Thus a target is detected farther away, precluding contact. A separate yellow setup LED, which lights to indicate nearing an unstable condition, more accurately positions the switch. For instance, with a flush-mounted switch, when the target is between 80 and 100% of the range, both the yellow setup and red output LEDs light to indicate marginal sensing conditions. With nonflush-mount units, the setup LED illuminates if the target is in the 100 to 115% range, where slight changes may trigger a switch.
When designing the quadro-norm plus, efector talked to maintenance people about technology that would make the proximity switches more productive. Their dc installation can be "flipped" for normally open or closed switching. Either type can be done with positive or negative switching, giving a total of four output functions. Thus, stocking of different units is reduced by 75%. And with ASIC programmability, setup time and inventory requirements are further eased.
The switches come in one-piece housings in threaded metal bodies 12, 18, and 30 mm in diameter. Flush-mountable sensing ranges are 4, 5, and 15 mm; 7, 12, and 22 mm.